Fabricating Poly(Vinylidene Fluoride) Based Composites With High Dielectric Permittivity, Low Loss, and High Electromagnetic Shielding Effectiveness by Melt Mixing With Polymethyl Methacrylate and Carbon Nanotubes

ABSTRACT Poly(vinylidene fluoride) (PVDF)/polymethyl methacrylate (PMMA)/carbon nanotubes (CNTs) composites with improved dielectric and electromagnetic shielding effectiveness properties are prepared by one‐step melt mixing. The microcosmic appearance and rheological behavior of PVDF/PMMA/CNTs composites illustrate that the CNTs formed well dispersion in the composite system. As a result, the dielectric permittivity of the PVDF/PMMA/CNTs composites increases with the increasing CNTs content. Meanwhile the dielectric loss is effectively restrained by obstructing the formation of conductive path due to the addition of PMMA. Moreover, beta polymorph is obtained in the PVDF/PMMA/CNTs composites, which also makes contribution to improving the dielectric properties of the composites. Therefore, with the addition of 3.5 vol% CNTs, the PVDF/PMMA/CNTs (FAC3.5) composite exhibits higher dielectric permittivity (13,686) and lower dielectric loss (0.625) than the PVDF/CNTs composite (9348 and 0.748, respectively) at frequency of 10 ⁴ Hz. Additionally, the FAC3.5 sample displays an outstanding total electromagnetic shielding effectiveness reaching 17 dB, which is six times that of pure PVDF and exceeds the critical 15 dB benchmark required for commercial applications. It suggests a novel strategy for preparing dielectric composites with both lower dielectric loss and high electromagnetic shielding effectiveness through precise modulation of the loading content, dispersion optimization, and interfacial engineering of nanoparticles.